Turbo-machine comprising a sealing system for a rotor

ABSTRACT

The invention relates to a turbo-machine ( 1 ) comprising a rotor ( 25 ) that extends along a rotational axis ( 15 ). Said rotor ( 25 ) has a peripheral surface ( 31 ) which is defined by the outer radial delimitation surface of the rotor ( 25 ) and has a receiving structure ( 33 ) as well as a first moving blade ( 13 A) and a second moving blade ( 13 B). Each moving blade comprises a blade footing ( 43 A,  43 B) and a blade platform ( 17 A,  17 B). The blade platform ( 17 A) of the first moving blade ( 13 A) and the blade platform ( 17 B) of the second moving blade ( 13 B) border one another, and a gap ( 49 ) is formed between the blade platforms ( 17 A,  17 B) and the peripheral surface ( 31 ). A sealing system ( 51 ) is provided in the gap ( 49 ) on the peripheral surface ( 31 ).

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/EP00/04317 which has an Internationalfiling date of May 12, 2000, which designated the United States ofAmerica, the entire contents of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The invention generally relates to a turbomachine including a sealingsystem for a rotor which extends along an axis of rotation, the rotorincluding a first rotor blade and a second rotor blade which adjoins thefirst rotor blade in the circumferential direction of the rotor.

BACKGROUND OF THE INVENTION

Rotatable rotor blades of turbomachines, for example of turbines orcompressors, are secured in various designs over the entirecircumference of the circumferential face of a rotor shaft which isformed, for example, by a rotor disk. A rotor blade usually has a mainblade, a blade platform and a blade root with a securing structure whichis fitted to the circumferential face of the rotor shaft in a suitablycomplementary recess, which is produced, for example, as acircumferential groove or an axial groove, so that the rotor blade isfixed in this way.

For design reasons, after the rotor blades have been inserted into therotor shaft, gaps are formed by the regions which adjoin one another,and in operation of a turbine these gaps give rise to leaking flows ofcoolant or of a hot action fluid which drives the rotor. Such gapsoccur, for example, between two adjacent blade platforms of rotor bladeswhich adjoin one another in the circumferential direction and betweenthe circumferential face of the rotor shaft and a blade platform whichradially adjoins the circumferential face. To limit the possible leakingflows, such as for example the escape of coolant, e.g. of cooling air,into the flow channel of a gas turbine, intensive searches are beingmade for suitable sealing concepts which are able to withstand thetemperatures which occur and the mechanical load caused by theconsiderable centrifugal forces acting on the rotating system.

DE 198 10 567 A1 has disclosed a sealing plate for a rotor blade of agas turbine. If cooling air which is fed to the rotor blade escapes intothe flow channel, this leads, inter alia, to a reduction in theefficiency of the gas turbine. The sealing plate, which is inserted intoa gap between the blade platforms of adjacent rotor blades, is intendedto prevent the leaking flows caused by the escape of cooling air. Thesealing is produced not only by the sealing plate but also by varioussealing pins which are likewise fitted between the blade platforms oftwo adjacent rotor blades. A multiplicity of sealing elements arerequired in order to achieve the desired sealing action preventingcooling air from escaping from the adjacent blade platforms.

U.S. Pat. No. 5,599,170 has described a sealing concept for a rotorblade of a gas turbine. A substantially radially extending gap and asubstantially axially extending gap are formed by two rotor blades whichadjoin one another and are attached to the circumferential face of arotor disk which can rotate about an axis. A sealing element seals theradial gap and, at the same time, the axial gap. For this purpose, thesealing element is inserted into a cavity which is formed by the bladeplatforms of the rotor blades. The sealing element has a first sealingface and a second sealing face which respectively adjoin the axial gapand the radial gap.

Moreover, the sealing element has a thrust face which extends obliquelywith respect to the radial direction. The thrust face directly adjoins areaction face which is formed as a partial area of a moveable reactionelement arranged in the cavity. The sealing action is produced by thecentrifugal forces acting on the moveable reaction element as a resultof the rotation of the rotor disk. The reaction element transmits to theinclined thrust face a force, the radially directed component of whichacts on the sealing element, so that the first sealing face seals theaxial gap, while the axially oriented component of the force on thesealing element leads to the second sealing face sealing the radial gap.This sealing concept is unable to prevent cooling air from escaping intothe flow passage of the gas turbine along the circumferential face ofthe rotor disk through gaps which are formed between the circumferentialface of the rotor disk and a blade platform of a rotor blade whichradially adjoins the circumferential face.

Similarly complex arrangements with one or more sealing elements, as aredescribed in DE 198 10 567 A1 or U.S. Pat. No. 5,599,170, are also usedin a turbomachine to prevent a flowing, hot action fluid, e.g. a hot gasor vapor, from entering gap regions and spaces in a rotor. Penetratingaction fluid of this type could lead to considerable damage to the rotorblade. To reduce this risk, generally a plurality of sealing elementsare inserted into the blade platform on that side of the blade platformof the rotor blade which faces the flow of action fluid.

GB 905,582 and EP 0 761 930 A1 each describe a turbomachine with aturbine rotor of disk design, in which rotor blades are attached to therotor disks by means of an axial fir-tree groove connection. Axialfixing of the rotor blades is produced by securing plates which arearranged in a fixed position on the end sides of the rotor disks, italso being possible to achieve a certain sealing action with respect tothe penetration of action fluid in the blade root/groove region.

SUMMARY OF THE INVENTION

The invention is based on an object of providing a sealing system for aflow machine. The flow machine preferably includes a rotor which extendsalong an axis of rotation and includes a first rotor blade and a secondrotor blade which adjoins the first rotor blade in the circumferentialdirection of the rotor.

The sealing system is in particular intended to actively limit thepossible leaking flows through gap regions and spaces of the rotor andto be able to withstand the thermal and mechanical loads which occur.

According to the invention, an object is achieved by a turbomachine,having a rotor which extends along an axis of rotation. The turbomachinepreferably includes a circumferential face, which is defined by theouter radial boundary surface of the rotor, and a receiving structure,as well as a first rotor blade and a second rotor blade. Each bladepreferably includes a blade root and a blade platform which adjoins theblade root, the blade root of the first rotor blade and the blade rootof the second rotor blade being inserted into the receiving structure,so that the blade platform of the first rotor blade and the bladeplatform of the second rotor blade adjoin one another. Further, a spaceis preferably formed between the blade platforms and the circumferentialface, in which turbomachine a sealing system is provided on thecircumferential face in the space.

The invention is based on a consideration that when a turbomachine isoperating, the rotor is exposed to a flowing hot action fluid. As aresult of the expansion, the hot action fluid applies work to the rotorblades and sets them in rotation about the axis of rotation. Therefore,the rotor with the rotor blades is subject to very high thermal andmechanical loads, in particular on account of the centrifugal forceswhich occur as a result of the rotation. A coolant, e.g. cooling air,which is usually fed to the rotor through suitable coolant feeds, isused to cool the rotor and in particular the rotor blades. In this case,leaking flows of both coolant and hot action fluid—what are known as gaplosses—may occur in the space. A space is in this case formed by thecircumferential face, which in this case is defined by the outer radialboundary surface of the rotor and by the platforms, arranged radiallyoutside the circumferential face, of two rotor blades which are arrangednext to one another in the circumferential direction of the rotor.

These leaking flows have a very disadvantageous effect on the coolingefficiency and the mechanical installation strength (quiet running andcreep rupture strength) of the rotor blades in the receiving structureof the circumferential face. In this context, leaking flows which areoriented along the axis of rotation (axial leaking flows), for examplealong the circumferential face, are of particular importance.Furthermore, leaking flows perpendicular to the axis of rotation (radialleaking flows), which are directed along a radial direction andtherefore substantially perpendicular to the circumferential face,should also be borne in mind.

The invention demonstrates a new way of effectively sealing a rotor witha first rotor blade and with a second rotor blade which adjoins thefirst rotor blade in the circumferential direction of the rotor in aturbomachine with respect to possible leaking flows. The arrangementtakes account of both axial and radial leaking flows. This is achievedby the fact that the sealing system is arranged in the space on thecircumferential face of the rotor.

As a result of the configuration described, the sealing system seals thespace which is formed between the blade platforms and thecircumferential face. The space extends in the radial and axial andcircumferential directions of the rotor. In this case, the axial extentof the gap is generally dominant, while its extent in thecircumferential direction is greater than the radial dimension. Theprecise geometry of the space is determined by the specificconfiguration of the mutually adjacent blade platforms and of thecircumferential face. The design of the sealing system described can beindividually adapted to the particular geometry and requirements withregard to the leaking flows which are to be restricted.

A significant advantage over conventional sealing concepts results fromthe sealing system being arranged on the circumferential face. As aresult, it is possible for the sealing system to directly adjoin thecircumferential face, so that a sealing action is produced. This isparticularly suitable for preventing leaking flows in the axialdirection along the circumferential face. By way of example, even thepenetration of a hot action fluid, e.g. the hot gas in a gas turbine,into the space is substantially prevented and an axially directed flowin the space along the circumferential face is considerably reduced.This protects the material of the rotor, in particular the material ofthe blade platforms, from the high temperatures and the possibleoxidizing and corrosive influences of the hot action fluid. In theradial direction the sealing system may be dimensioned in such a waythat it directly adjoins the adjacent blade platforms and a sealingaction is achieved. In this way, axial leaking flow is virtuallycompletely prevented.

Temperature gradients in the region of the rotor blade attachment areaare avoided by preventing leaking flows of hot action fluid and/or ofcoolant in the space by means of the sealing system. As a result, anythermal stresses resulting from impeded thermal expansion of rotorcomponents which adjoin one another in the event of temperaturedifferences are reduced. The blade root of a rotor blade and thereceiving structure of the rotor which receives the rotor blade andfixes it can therefore be produced with significantly lower tolerances.A lower tolerance has an advantageous effect on the mechanicalinstallation stability of the rotor blade and the quiet running of therotor. In particular, form fits which are provided for the purpose ofsecuring the blade root in the receiving structure can be provided witha lower clearance, which also correspondingly reduces possible leakingflows through the form fit.

A further advantage is the ease of producing and installing the sealingsystem. Since the sealing system is provided on the circumferentialface, it is not necessarily fixedly coupled to a rotor blade.Installation or repair work on a rotor blade, such as for example,exchanging a rotor blade, can therefore be carried out without greatdifficulty. The sealing system remains unaffected by this work and cantherefore be used a number of times.

In a preferred configuration of the turbomachine, the rotor has a rotordisk, which includes the circumferential face and the receivingstructure, the circumferential face including a firstcircumferential-face edge and a second circumferential-face edge, whichlies opposite the first circumferential-face edge along the axis ofrotation, the receiving structure including a first rotor-disk grooveand a second rotor-disk groove, which is at a distance from the firstrotor-disk groove in the circumferential direction of the rotor disk,and the blade root of the first rotor blade being inserted into thefirst rotor-disk groove and the blade root of the second rotor bladebeing inserted into the second rotor-disk groove.

Therefore, the securing of the rotatable rotor blade is such that, whenthe turbomachine is operating, it is able to absorb the blade stressescaused by flow and centrifugal forces and by blade vibrations with ahigh degree of reliability and to transmit the forces which arise to therotor disk and ultimately to the entire rotor. The rotor blade can besecured, by way of example, by axial grooves, each rotor blade beingclamped individually in a dedicated rotor-disk groove which extendssubstantially in the axial direction. For low loads, e.g. in the case ofaxial compressor rotor blades of compressors, simple ways of securingthe rotor blade, for example using a dovetail or Laval root, arepossible. For steam-turbine end stages with long rotor blades andcorrespondingly high blade centrifugal forces, as well as the so-calledplug-in root, the axial fir-tree root is also suitable. The axialfir-tree securing is preferably also employed for rotor blades which aresubject to high thermal stresses in gas turbines.

In the preferred configuration described above, the circumferential facehas a first circumferential-face edge and a second circumferential-faceedge as partial regions. Based on the direction of flow of a flowing hotaction fluid, in particular of the hot gas in a gas turbine, in thiscase, by way of example, the first circumferential-face edge is arrangedupstream and the second circumferential-face edge is arrangeddownstream. Depending on the particular design details and requirementswith regard to the sealing action to be achieved, this geometricdivision allows a configuration and arrangement of the sealing systemover various partial regions of the circumferential face.

The sealing system is preferably arranged on the firstcircumferential-face edge and/or on the second circumferential-faceedge. Arranging the sealing system on the first, for example upstream,circumferential-face edge primarily limits the penetration of flowinghot action fluid into the space and therefore prevents damage to therotor blade. Arranging the sealing system on the second, downstreamcircumferential-face edge serves predominantly to prevent the escape ofcoolant, for example cooling air which is under a certain pressure inthe space, in the axial direction along the circumferential face overthe second circumferential-face edge into the flow passage. Since thehot action fluid expands in the direction of flow, the pressure of thehot action fluid is continuously reduced in the direction of flow. Acoolant which is under a certain pressure in the space will thereforeescape from the space in the direction of the lower ambient pressure,i.e. at the downstream circumferential-face edge. Arranging the sealingsystem on the first circumferential-face edge and on the secondcircumferential-face edge closes off the space and accordingly offershighly reliable protection both against the penetration of hot actionfluid into the space and the escape of coolant from the space.

Preferably, a circumferential-face central region, which is bordered inthe axial direction by the first circumferential-face edge and thesecond circumferential-face edge, is formed on the circumferential face,the sealing system being arranged at least partially on thecircumferential-face central region. The circumferential-face centralregion forms a partial region of the circumferential face. Therefore,there are various options for arranging the sealing system on variouspartial regions of the circumferential face together with the first andsecond circumferential-face edges. Depending on design details andrequirements with regard to the sealing action to be achieved, it ispossible to determine a suitable solution, with the sealing systemarranged on various partial regions. Combinations of various partialregions are also conceivable when arranging the sealing system.Therefore, with regard to adapting to specific requirements in terms ofthe sealing action to be achieved, the sealing system described offers avery high degree of flexibility.

The sealing system preferably has a sealing element which extends in thecircumferential direction. The space extends substantially in the radialand axial directions and in the circumferential direction of the rotor.A sealing element which extends along the circumferential direction ofthe rotor in the space is particularly suitable for preventing thepossibility of axial leaking flows of coolant and/or also of hot actionfluid with a high degree of efficiency. For example, an axial leakingflow in the upstream direction, for example a hot gas leaking out of theflow passage of a gas turbine, which spreads out along thecircumferential face is effectively prevented by the sealing element. Inthis case, the leaking flow is delayed by the obstacle in the space andultimately comes to a standstill on that side of the sealing elementwhich faces the leaking flow (simple restrictor). That side of thesealing element which is remote from the leaking flow and that part ofthe space which adjoins it in the axial direction are alreadyeffectively protected from being exposed to the leaking medium, e.g. hotaction fluid or coolant, by the simple sealing element.

A considerable improvement to the simple solution described above with asealing element extending in the circumferential direction results fromcombining the sealing element with one or more further sealing elements.In a preferred configuration, at least one further sealing element isprovided, which extends in the circumferential direction and is arrangedat an axial distance from the sealing element. This multiple arrangementof sealing elements considerably reduces possible leaking flows in thespace. In particular, it is possible, for example, for the sealingelement to be arranged on the first circumferential-face edge and forthe further sealing element to be arranged on the secondcircumferential-face edge.

As a result, the space is sealed both upstream and downstream withrespect to axial leaking flows. The space is in particular protectedvery effectively against the possibility of the penetration of hotaction fluid both from the upstream region at higher pressure and fromthe downstream region at lower pressure in the flow passage. At the sametime, the sealed space can be used effectively by a coolant, e.g.cooling air. The coolant is fed to the space under pressure and is usedprimarily for efficient internal cooling of the highly thermallystressed rotor, the blade platform and the main blade which radiallyadjoins the blade platform.

A further advantageous use for the pressurized coolant in the spaceincludes utilizing its barrier action with respect to the hot actionfluid in the flow passage. The design of the sealing elements and theselection of the pressure of the coolant in the space mean that thepressure difference between the coolant and the hot action fluid isadequately low yet sufficiently high to achieve a barrier action withrespect to the hot action fluid. For this purpose, the pressure of thecoolant which prevails in the space must be only slightly above theupstream pressure of the hot action fluid. The greater the sealingaction of the sealing elements, the smaller any residual leaking flowsof coolant into the flow passage become.

The sealing element preferably engages in a recess, in particular in agroove, in the circumferential face. The sealing element is preventedfrom falling out and/or from being thrown out under the action ofcentrifugal forces in steady-state operation or in the event of atransient load on the turbomachine is achieved by the fact that thesealing element engages in a suitable recess. Furthermore, the recessproduces a sealing surface, which is expediently designed as a partialarea of the recess, on the circumferential face. In the case of agroove, this sealing surface is formed, for example, at the base of thegroove. To achieve the optimum sealing action when the sealing elementis active, the sealing surface is produced with a suitably low andwell-defined surface roughness. After the actual production of thegroove, for example by abrading material from the circumferential faceby means of a milling or turning operation, a sealing surface with thedesired roughness can be produced on the base of the groove bypolishing.

The sealing element is preferably moveable in the radial direction. Thishas the effect of causing the sealing element to move away from the axisof rotation of the rotor in the radial direction under the action ofcentrifugal force. This property is deliberately exploited in order toachieve a significantly improved sealing action at the blade platform ofa rotor blade. Under the action of centrifugal force, the sealingelement comes into contact with the blade platforms which are at aradial distance from the circumferential face and adjoin one another inthe circumferential direction and is pressed firmly onto the bladeplatforms. The radial mobility of the sealing element can be ensured bysuitable dimensioning of the recess and of the sealing element.Furthermore, it is advantageous that, as a result, the sealing elementcan be removed and, if appropriate, exchanged without problems for anymaintenance to be carried out or in the event of failure of the rotorblade without using additional tools and without the risk of the sealingelement becoming stuck as a result of oxidizing or corrosive attackunder high operating temperatures. Furthermore, a certain tolerance ofthe sealing element which engages in the recess, in particular in thegroove, is very useful, since as a result thermal expansion ispermitted, and therefore thermally induced stresses are avoided in therotor.

The sealing element preferably includes a first partial sealing elementand a second partial sealing element, the first partial sealing elementand the second partial sealing element engaging in one another. Thepartial sealing elements may be designed in such a way that theyprovide, in a particular manner, a partial sealing function fordifferent regions in the space which are to be sealed. These differentregions in the space are formed, for example, by suitable sealingsurfaces at the base of the groove, on the blade platform of the firstrotor blade or on the blade platform of the second rotor blade. As aresult of being arranged as a pair of partial sealing elements, thepartial sealing elements combine to form one sealing element, thesealing action of the pair being greater than that of a single partialsealing element. By suitably adapting the design of the partial sealingelements to the partial regions in the space which are to be sealed, itis possible for the sealing action of the paired partial sealingelements to be greater than that which can be achieved, for example,with a single-piece sealing element.

Preferably, the first partial sealing element and the second partialsealing element can move in the circumferential direction relative toone another. This provides a matched system comprising partial sealingelements. The relative movement of the partial sealing elements in thecircumferential direction allows matched engagement of the partialsealing elements in one another as a function of the thermal and/ormechanical loads acting on the rotor. The matched system of partialsealing elements may be designed in such a way that under the action ofthe external forces, such as for example the centrifugal force and thenormal and bearing forces, it to a certain extent adjusts itself inorder to provide its sealing action. Furthermore, possible thermally ormechanically induced stresses are compensated for significantly moresuccessfully by the movable pair of partial sealing elements.

In a preferred configuration, the first partial sealing element and thesecond partial sealing element each have a disk-sealing edge, whichadjoins the circumferential face, and a platform-sealing edge, whichadjoins the blade platform. In this case, the platform-sealing edge mayin each case be further functionally divided into partialplatform-sealing edges. By way of example, for a partial sealing elementthere may be a first partial platform-sealing edge and a second partialplatform-sealing edge, the first partial platform-sealing edge beingadjacent to the blade platform of the first rotor blade and the secondpartial platform-sealing edge being adjacent to the blade platform ofthe second rotor blade. This functional division makes it easy to adaptthe.design of the partial sealing elements to the particularinstallation geometry of the first and second rotor blades in thereceiving structure. Suitable designing of the partial sealing elementensures that the disk-sealing edge is sealed against the circumferentialface and the platform-sealing edge is sealed against the blade platformof the rotor blade, producing the best possible form fit.

The paired arrangement of the first and second partial sealing elementsto form a sealing element provides a particularly effective seal. Thefirst and second partial sealing elements preferably overlap oneanother, with the platform-sealing edge and the disk-sealing edge of thefirst partial sealing element being adjacent to the platform-sealingedge and disk-sealing edge, respectively, of the second partial sealingelement. As a result, the paired arrangement of the two partial sealingelements produces a good positive lock, and consequently the sealingelement produces a good seal against the penetration of hot action fluidinto the space and/or the escape of coolant into the flow passage.

The sealing element is preferably made from a material which is able towithstand high temperatures, in particular from a nickel-base orcobalt-base alloy. These alloys also have sufficient elastic deformationproperties. The result is that the material of the sealing element, inorder to avoid contamination or diffusion damage and to ensure a uniformthermal expansion of the rotor, in particular of the blade platform ofthe rotor blade, is selected to match the material of the rotor.

In a preferred configuration, the sealing system has a labyrinth sealingsystem, in particular a labyrinth gap sealing system. The action of alabyrinth sealing system is based on the most effective possiblerestriction of the hot action fluid and/or of the coolant in the sealingsystem and a resulting substantial prevention of an axially directedleaking flow (leak mass flow) through the space. In this case, aresidual leaking flow through existing sealing gaps, as generally occurwith labyrinth gap seals, can be calculated taking account of theso-called bridging factor. With the same flow parameters upstream anddownstream of the seal and identical principal dimensions of thelabyrinth sealing system (sealing gap diameter, sealing gap width,overall axial length of the seal), labyrinth gap sealing systems, whichare also referred to as look-through seals, compared to so-calledtongue-and-groove sealing systems have a leaking flow through thesealing gap which is up to 3.5 times greater. However, on account of thesealing gap which remains, labyrinth gap sealing systems have theconsiderable advantage over the tongue-and-groove sealing systems thatthey themselves are suitable for considerable thermally and/ormechanically induced relative expansions in the rotor.

The sealing system is preferably produced integrally, in particular byremoving material from the rotor disk. If the sealing system isdesigned, for example, as a labyrinth sealing system, it is produced bymeans of at least two sealing elements on the circumferential surface,which extend in the circumferential direction of the rotor disk and areat an axial distance from one another. These sealing elements may beformed by metal restrictor plates which are turned out of the solid. Theintegral production method has the advantage that there is no need foran additional joining element between the labyrinth sealing system andthe circumferential face. Therefore, in terms of process engineering,the rotor disk can be machined and the labyrinth sealing system producedin a single step carried out on a lathe, which is very inexpensive.Furthermore, thermally induced stresses between the rotor disk and thelabyrinth sealing system do not play any role, since only one materialis used. Alternative configurations of the sealing element, for exampleby using a metal restrictor plate welded onto the rotor disk or by usinga metal restrictor plate which is jammed into a groove into thecircumferential face, are also possible.

On its outer radial end, the sealing element preferably has a sealingpoint, in particular a knife edge.

Residual leaking flows through the space are decisively influenced bythe sealing gap width which can be achieved, i.e. for example thedistance between the outer radial end of the sealing element and theadjoining blade platform which is to be sealed. To make the sealing gapwidth as small as possible, it is provided for the outer radial end ofthe sealing element to be sharpened. In this case, it is possible, inparticular to bridge the sealing gap, by producing the sealing point orthe knife edge with a small dimension compared to the radialinstallation dimension of the blade platform. By drawing the sealing tipor the knife edge onto the blade platform, the sealing gap is bridgedwhen the rotor blade is inserted into the receiving structure, forexample into an axial groove in a rotor disk. In this way, the sealinggap is closed off, an improved seal is achieved and the axial leakingflow is further reduced. Compared to conventional designs, therefore, itis also possible to considerably reduce the installation dimension of arotor blade in the receiving structure. The minimum installationdimension which has hitherto been customary of between approximately 0.3and approximately 0.6 mm can be reduced to approximately 0.1 toapproximately 0.2 mm by using the new design, i.e. is reduced byapproximately two thirds.

In a preferred configuration, a gap sealing element is provided forsealing a substantially axially extending gap, the gap being formedbetween the blade platform of the first rotor blade and the bladeplatform of the second rotor blade and being in flow communication withthe space. The gap sealing element prevents a leaking flow through thegap. A leaking flow of this type is substantially radially directed andmay be oriented both radially outward from the space through the gap andradially inward through the gap into the space.

In this case, various designs are possible:

For example, if the flow passage of the turbomachine, e.g. of acompressor or a gas turbine, adjoins the gap in the radially outwarddirection, the gap sealing element prevents the penetration of theaction fluid, e.g. of the hot gas in a gas turbine, radially inward intothe space through the gap. As a result, the rotor, in particular therotor blade, is protected from oxidizing and/or corrosive attack in thespace. At the same time the gap sealing element prevents coolant, e.g.cooling air, from escaping from the space through the gap radiallyoutward into the flow passage.

In an alternative configuration, a cavity may also adjoin the gap on theradially outer side, this cavity being formed by the first and secondrotor blades which adjoin one another in the circumferential direction(known as the box design of a rotor blade). In this case, the gapsealing element firstly prevents the possibility of hot action fluidpenetrating from the space through the gap radially outward into thecavity. Secondly, the cavity which is sealed by the gap sealing elementcan be acted on by a coolant, e.g. cooling air. This coolant is underpressure in the cavity and is available, for example, for efficientinternal cooling of the rotor blade which is subject to high thermalloads or for other cooling purposes. A further advantageous use of thepressurized coolant in the cavity consists in utilizing its barrieraction with respect to the hot action fluid in the flow passage.

The gap sealing element is preferably produced by a metal gap sealingplate which has a gap-sealing edge which engages in the gap under theaction of centrifugal force and closes off the gap. Designing the gapsealing element as a metal gap sealing plate represents a simple andinexpensive solution. In this case, for example, a design as a thinmetal strip which has a longitudinal axis and a transverse axis ispossible. In this case, the gap-sealing edge extends substantiallycentrally on the metal strip along the longitudinal axis and can beproduced in a simple way by bending over the metal strip. The gapsealing element is expediently arranged in the space. When theturbomachine is operating, the gap sealing element is then, as a resultof the rotation, pressed firmly by the radially outwardly directedcentrifugal force against the mutually adjoining blade platform, thegap-sealing edge engaging in the gap and effectively sealing the latter.

The gap sealing element is preferably made from a material which is ableto withstand high temperatures, in particular from a nickel-base orcobalt-base alloy. Moreover, these alloys also have sufficient elasticdeformation properties. The material of the gap sealing element isselected to match the material of the rotor, with the result thatcontamination or diffusion damage is avoided. Furthermore, uniformthermal expansion or contraction of the rotor, in particular of theblade platform of the rotor blade, is ensured.

The gap sealing element preferably radially adjoins the sealing system.The combination of the gap sealing element with a sealing systemarranged on the circumferential face, in particular with a labyrinthsealing system, results in particularly effective sealing of the spaceagainst the possibility of leaking flows of hot action fluid and/or ofcoolant. In particular, as a result a centrifugally assisted sealingaction of the gap sealing element is retained in order to seal anaxially extending gap. In this combination, the sealing system reducesthe substantially axially oriented leaking flows, while the gap sealingelement reduces the substantially radially directed leaking flows.Furthermore, this separation of functions readily allows flexible designadjustment to different rotor geometries. Consequently, the gap sealingelement and the sealing system complement one another very effectively.

In a preferred configuration, in the turbomachine with the rotorextending along an axis of rotation, the receiving structure is producedby a circumferential groove, the circumferential face having a firstcircumferential face and a second circumferential face which liesopposite the first circumferential face along the axis of rotation,these faces in each case axially adjoining the circumferential groove,the sealing system being provided in the space on the first and/orsecond circumferential face.

When the turbomachine is operating, the means of securing the rotorblades must with great reliability absorb the blade stresses caused byflow and centrifugal forces and by the vibrations of the blade and musttransmit the forces which are generated to the rotor disk and ultimatelyto the entire rotor. In addition to securing the rotor blade in an axialgroove, an arrangement in which the rotor blade is secured in acircumferential groove is also in widespread use, particularly for lowand medium stresses. In this case, various configurations are knowndepending on the stress (c.f. I. Kosmorowski and G. Schramm, “TurboMaschinen” [Turbomachines], ISBN 3-7785-1642-6, published by Dr. AlfredHüthig Verlag, Heidelberg, 1989, pp. 113-117).

By way of example, for short rotor blades with low centrifugal forcesand bending moments, the so-called hammerhead connection method, whichis easy to produce, is used. In the case of longer rotor blades andtherefore higher blade centrifugal forces, in the case of rotors of diskdesign, particular design measures have to be used to prevent the rotordisk from bending in the region of the first and second circumferentialfaces at the level of the circumferential groove. This can be achieved,for example, with the aid of a rotor disk which is of solid design atthe level of the circumferential groove, a hooked hammerhead root or ahooked sliding root. However, a more efficient transmission of forces tothe rotor disk is achieved, for example, by the circumferential fir-treesecuring device. In any event, the described concept for sealing thespace can be transferred very flexibly to a rotor in which the rotorblade is secured in a circumferential groove.

The turbomachine is preferably a gas turbine.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below, by way of example, withreference to exemplary embodiments illustrated in the drawing, in which,in some cases diagrammatically and in simplified form:

FIG. 1 shows a half-section through a gas turbine with compressor,combustion chamber and turbine,

FIG. 2 shows a perspective view of part of a rotor disk of a rotor,

FIG. 3 shows a perspective view of part of a rotor disk with insertedrotor blade,

FIG. 4 shows a side view of a rotor blade with sealing system,

FIGS. 5A-5D show various views of a first partial sealing element of asealing element illustrated in FIG. 4,

FIGS. 6A-6D show various views of a second partial sealing element of asealing element illustrated in FIG. 4,

FIG. 7 shows an axial plan view of part of a rotor with sealing element,

FIG. 8 shows an axial plan view of part of a rotor with an alternativeconfiguration of the sealing element to that shown in FIG. 7,

FIG. 9 shows a side view of a rotor blade with a labyrinth sealingsystem,

FIG. 10 shows a side view of a rotor blade with an alternativeconfiguration of the labyrinth sealing system of that shown in FIG. 9,

FIG. 11 shows a perspective view of part of a rotor disk with insertedrotor blade and with a gap sealing element,

FIG. 12 shows part of a view of the arrangement shown in FIG. 11, onsection line XII—XII,

FIG. 13 shows a perspective view of a rotor shaft with circumferentialgrooves,

FIG. 14 shows a sectional view of part of a rotor with circumferentialgroove and with inserted rotor blade,

FIG. 15 shows a sectional view of part of a rotor with an alternativeconfiguration of the rotor-blade securing to that shown in FIG. 14.

In the individual figures, identical reference numerals have the samemeaning.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a half-section through a gas turbine 1. The gas turbine 1includes a compressor 3 for combustion air, a combustion chamber 5 withburners 7 for a liquid or gaseous fuel, and a turbine 9 for driving thecompressor 3 and a generator, which is not shown in FIG. 1. Fixed guideblades 11 and rotatable rotor blades 13 are arranged in the turbine 9 onrespective rings, which extend radially and are not shown in thehalf-section, along the axis of rotation 15 of the gas turbine 1. A pairof a ring of guide blades 11 (guide-blade ring) and a ring of rotorblades 13 (rotor-blade ring) which follow one another along the axis ofrotation 15 are referred to as a turbine stage. Each guide blade 11 hasa blade platform 17 which is arranged on the inner turbine casing 19 inorder to fix the corresponding guide blade 11. The blade platform 17represents a wall element in the turbine 9. The blade platform 17 is acomponent which is subject to high thermal loads and forms the outerboundary of the flow passage 21 in the turbine 9. The rotor blade 13 isattached to the turbine rotor 23, which is arranged along the axis ofrotation 15 of the gas turbine 1, by means of a corresponding bladeplatform 17.

The turbine rotor 23 may be assembled, for example, from a plurality ofrotor disks which are not shown in FIG. 1, receive the rotor blades 13,are held together by a tie rod (not shown) and are centered, in such amanner that they are able to tolerate thermal expansion, on the axis ofrotation 15 by use of radial serrations. Together with the rotor blades13, the turbine rotor 23 forms the rotor 25 of the turbomachine 1, inparticular of the gas turbine 1. In the region of the gas turbine 1, airL is sucked in from the environment. The air L is compressed in thecompressor 3 and as a result is simultaneously preheated. In thecombustion chamber 5, the air L is brought together with the liquid orgaseous fuel and is burned. A fraction of the air L which has beenremoved from the compressor 3 at suitable removal device 27 is used ascooling air K to cool the turbine stages, the first turbine stage beingexposed, for example, to a turbine inlet temperature of approximately750° C. to 1200° C. Expansion and cooling of the hot action fluid A,referred to below as hot gas A, which flows through the turbine stagesand in the process sets the rotor 25 in rotation, take place in theturbine 9.

FIG. 2 shows a perspective view of part of a rotor disk 29 of a rotor25. The rotor disk 29 is centered along the axis of rotation 15 of therotor 25.

The rotor disk 29 includes a receiving structure 33 for rotor blades 13of the gas turbine 1 to be secured in. The receiving structure 33 isproduced by recesses 35, in particular by grooves, in the rotor disk 29.The recess 35 is in this case designed as an axial rotor-disk groove 37,in particular as an axial fir-tree groove. The rotor disk 29 has acircumferential face 31 which is arranged at.the outer radial end of therotor disk 29. The circumferential face 31 is defined by the outerradial boundary surface of the rotor 25 or of the rotor disk 29. Thecircumferential face 31 defined in this way does not include thereceiving structure 33 which is designed as an axial rotor-disk groove37. A first circumferential-face edge 39A and a secondcircumferential-face edge 39B are formed on the circumferential face 31.The first circumferential-face edge 39A lies opposite the secondcircumferential-face edge 39B on the circumferential face 31 along theaxis of rotation 15. A circumferential-face central region 41, which inthe axial direction is bordered by the first circumferential-face edge39A and the second circumferential-face edge 39B, is formed on thecircumferential face 31.

A perspective view of part of a rotor disk 29 with inserted rotor blade13A is illustrated in FIG. 3. The rotor disk 29 has rotor-disk grooves37A, 37B, which are open toward its circumferential face 31, over itsentire circumference; these grooves run substantially parallel to theaxis of rotation 15 of the rotor 25, although they may also be inclinedwith respect to this axis. The rotor-disk grooves 37A, 37B are providedwith undercuts 59. The blade root 43A of a rotor blade 13A is insertedinto a rotor-disk groove 37A along the insertion direction 57 of therotor-disk groove 37A. The blade root 43A is supported, by usinglongitudinal ribs 61, against the undercuts 59 of the rotor-disk groove37A. In this way, when the rotor disk 29 rotates about the axis ofrotation 15, the rotor blade 13A is held securely with regard to thecentrifugal forces which occur in the direction of the longitudinal axis47 of the rotor blade 13A. In the radially outward direction, along thelongitudinal axis 47 of the blade root 43A, the rotor blade 13A has awidened region, known as the blade platform 17A. The blade platform 17Ahas a disk-side base 63 and an outer side 65 which is on the oppositeside from the disk-side base 63. On the outer side 65 of the bladeplatform 17A there is a main blade 45 of the rotor blade 13A. The hotgas A which is required for operation of the rotor 25 flows past themain blade 45 and, in the process, generates a torque on the rotor disk29. At high operating temperatures of the rotor 25, the main blade 45 ofthe rotor blade 13A requires an internal cooling system, which is notshown in FIG. 3. In this case, a coolant K, for example cooling air K,is passed through a feed line (not shown) through the rotor disk 29 intothe blade root 43A of the rotor blade 13A and, from there, to suitablesupply lines (likewise not shown in FIG. 3) of the internal coolingsystem.

To prevent the coolant K, in particular the cooling air K, from escapingprematurely in the region of the blade root 43A and of the bladeplatform 17, a sealing system 51 is provided. The sealing system 51 isarranged on the circumferential face 31 on the secondcircumferential-face edge 39B. The sealing system 51 includes a sealingelement 53 which extends in the circumferential direction of the rotordisk 29. A further sealing element 55 is preferably provided and extendsin the circumferential direction of the rotor disk 29, at an axialdistance from the sealing element 53.

The sealing element 53 and the further sealing element 55 each engage ina recess 35, in particular in a groove, in the circumferential face 31.The sealing system 51 seals the space 49 which is formed between theblade platform 17A of the rotor blade 13A and a blade platform 17B of asecond rotor blade 13B, which is illustrated by dashed lines and isinserted into a second rotor-disk groove 37B, which is at a distancefrom the first rotor-disk groove 37A in the circumferential direction ofthe rotor disk 29, and the circumferential face 31. This substantiallyprevents the hot gas A from passing axially over the secondcircumferential-face edge 39B into the space 49 and damaging the rotorblade 13A, 13B in the region of the blade root 43A, 43B or the bladeplatform 17A, 17B. Furthermore, coolant K is prevented from escapingfrom the space 49 in the axial direction along the circumferential face31 over the second circumferential-face edge 39B.

FIG. 4 shows a side view of a rotor blade 13 with sealing system 51. Thesealing system 51 is illustrated as a partial section in FIG. 4. Thesealing system 51 is arranged on the first circumferential-face edge 39Aand on the second circumferential-face edge 39B in the space 49. Basedon the direction of flow of the hot gas A, the firstcircumferential-face edge 39A is located upstream on the circumferentialface 31 of the rotor disk 29, and the second circumferential-face edge39B is located downstream.

The arrangement of the sealing system 51 on the first, upstreamcircumferential-face edge 39A firstly restricts the penetration offlowing hot gas A into the space 49. This prevents damage to the rotorblade 13 and to the rotor disk 29 in the region of the circumferentialface 31. Arranging the sealing system 51 on the second, downstreamcircumferential-face edge 39B serves primarily to prevent as efficientlyas possible the escape of a coolant K, e.g. cooling air K which is undera certain pressure in the space 49, in the axial direction along thecircumferential face 31 over the second circumferential-face edge 39Binto the flow passage.

When the rotor 25 is operating, the hot gas A expands in the directionof flow. As a result, the pressure of the hot gas A is continuouslyreduced in the direction of flow. A coolant K which is under a certainpressure in the space 49 will therefore escape from the space 49 towardthe lower ambient pressure, i.e. at the downstream, secondcircumferential-face edge 49B. The sealing system 51 on the firstcircumferential-face edge 39A and on the second circumferential-faceedge 39B seals the space 49 in both directions. Therefore, this designoffers a particularly high degree of protection both against thepenetration of hot gas A into the space 49 and against the escape ofcoolant K from the space 49.

On the first circumferential-face edge 39A, the sealing system 51includes a sealing element 53 which extends in the circumferentialdirection of the rotor 29. The sealing element 53 engages in a recess35, in particular in a groove, which is machined into thecircumferential face 31. At the second circumferential-face edge 39B,the sealing system 51 includes as a sealing element 53 which extends inthe circumferential direction. A further sealing element 55 is providedon the second circumferential-face edge 39B. The further sealing element55 extends in the circumferential direction of the rotor disk 29 and isarranged at an axial distance from the sealing element 53.

Forming the sealing system 51 by using one or more sealing elements 53,55 is particularly suitable for more efficient prevention of thepossibility of axial leaking flows of coolant K and/or of hot gas A inthe space 49. For example, an axial leaking flow directed upstream, e.g.of the hot gas A out of the flow passage of a gas turbine 1, which flowsinto the space 49 over the first circumferential-face edge 39A along thecircumferential face 31, is effectively prevented from penetrating bythe sealing element 51 arranged on the first circumferential-face edge39. At the same time, an axial leaking flow which is directed out of thespace 49 along the second circumferential-face edge 39B is reliablyprevented from occurring by the obstacle in the form of the sealingelements 53, 55.

This multiple arrangement of sealing elements 53, 55 considerablyreduces the possibility of leaking flows in the space 49. Therefore, thesealed space 49 can be used efficiently for a coolant K, e.g. coolingair K. This can be pressurized and can then be used for efficientinternal cooling of the rotor 25 which is exposed to high thermal loads,in particular of the blade platform 17 and of the main blade 45 whichadjoins the blade platform along the longitudinal axis 47. A furtheradvantageous use of the pressurized coolant K in the space 49 isprovided by the blocking action with respect to the hot gas A in theflow passage. This blocking action of the coolant K substantiallyprevents hot gas A from penetrating into the space 49.

The sealing elements 53, 55 are each arranged so that they can move inthe radial direction in the recess 35, so that when the rotor 25 isoperating, on account of the centrifugal force acting on the sealingelements 53, 55, an improved sealing action compared to conventionaldesigns is achieved. The sealing elements 53, 55 will move radiallyoutward, parallel to the longitudinal axis 47, under the action ofcentrifugal force. In the process, the disk-side base 63 of the bladeplatform 17 is very effectively sealed with respect to possible axialleaking flows out of the space 49 or into the space 49. The radialmobility of the sealing elements 53, 55 can be provided by suitablydesigning the recess 35 and the sealing elements 53, 55. As a result,the sealing elements 53, 55 can also be removed and, if necessary,exchanged without problems for any maintenance which may be required orin the event of a failure of the rotor blade 13, without having to useadditional tools and without the risk of the sealing element 53 becomingjammed as a result of an oxidizing or corrosive attack at high operatingtemperatures.

Furthermore, a certain tolerance of the sealing elements 53, 55 which ineach case engage in a recess 35, in particular in a groove, is veryadvantageous. This allows thermal expansion and therefore preventsthermally induced stresses. The sealing element 53, 55 preferablyincludes a first partial sealing element 67A and a second partialsealing element 67B. The first partial sealing element 67A and thesecond partial sealing element 67B engage in one another. By theirpaired arrangement, the partial sealing elements 67A, 67B complement oneanother to form a sealing element 53, 55 in a particular way, thesealing action achieved by the paired partial sealing elements 67A, 67Bbeing greater than that achieved by an individual partial sealingelement 67A, 67B. A particularly advantageous configuration of thepartial sealing elements 67A, 67B on the regions in the space 49 whichare to be sealed in each case ensures that the sealing action achievedby the paired arrangement is greater than that which could be achievedwith, for example, a single-piece sealing element 53. A possible,particularly advantageous configuration of the partial sealing elements67A, 67B is described below with reference to FIGS. 5A to 5D and FIGS.6A to 6D.

The sealing element 53, 55 shown in FIG. 4, in a preferredconfiguration, includes two partial sealing elements 67A, 67B whichengage in one another. FIGS. 5A to 5D show various views of the firstpartial sealing element 67A:

FIG. 5A shows a perspective view of the first partial sealing element67A. The first partial sealing element 67A preferably includes adisk-sealing edge 69 and a platform-sealing edge 71 which lies oppositethe disk-sealing edge 69. In the installed state of the partial sealingelement 67A, the disk-sealing edge 69 adjoins the circumferential face31, and the platform-sealing edge 71 adjoins the disk-side base 63 ofthe blade platform 17. FIG. 5B shows a view of the disk-sealing edge 71of the first partial sealing element 67A, FIG. 5C shows a plan view ofthe first partial sealing element 67A, and FIG. 5D shows a side view.

The platform-sealing edge 71 preferably includes a first partialplatform-sealing edge 71A and a second partial platform-sealing edge71B. This dividing of the platform-sealing edge 71 into two partialplatform-sealing edges 71A, 71B makes it easy to adapt the design of thefirst partial sealing element 67A to the particular installationgeometry of a rotor blade 13 and of a further rotor blade 13B in a rotordisk 29 (cf. FIG. 3 and FIG. 4).

The second partial sealing element 67B is preferably designed in acorresponding way. FIGS. 6A to 6D show various views of the secondpartial sealing element 67B of a sealing element 53 illustrated in FIG.4. In a similar way to the first partial sealing element 67A, the secondpartial sealing element 67B preferably includes a disk-sealing edge 69and a platform-sealing edge 71 which lies opposite the disk-sealing edge69. In this case, the platform-sealing edge 71 is further divided infunctional terms into partial platform-sealing edges 71A, 71B. A firstpartial platform-sealing edge 71A and a second partial platform-sealingedge 71B are preferably provided. Each of the partial sealing elements67A, 67B is designed in such a way that its center of gravity isarranged adjacent to precisely one of the partial platform-sealing edges71A, 71B assigned to the corresponding partial sealing element 67A, 67B.This is achieved by using a stepped design of each of the partialsealing elements 67A, 67B, with a region of reduced material thicknessand a region of greater material thickness, each region being assignedto precisely one partial platform-sealing edge 71A, 71B.

The result of this special design of the partial sealing elements 67A,67B is that the disk-sealing edge 69 is well sealed against thecircumferential face 31 and the platform-sealing edge 71, or each of thepartial platform-sealing edges 71A, 71B, is/are sealed against the bladeplatform 17 of the rotor blade 13, with a form fit and improvedmechanical stability being produced. The first partial sealing element67A, and the second partial sealing element 67B are preferably arrangedin pairs to form a sealing element 53. The result is a very efficientseal. The partial sealing elements 67A, 67B are preferably designed insuch a way that, in the installed state, they engage in one another andoverlap one another, the platform-sealing edge 71 and the disk-sealingedge 69 of the first partial sealing element 67A being adjacent to theplatform-sealing edge 71 and the disk-sealing edge 69, respectively, ofthe second partial sealing element 67B. The partial sealing elements67A, 67B are preferably arranged in such a way that regions of differentmaterial thickness come into contact with one another.

Therefore, the paired arrangement of the two partial sealing elements67A, 67B produces a very good form fit, and consequently the sealingelement 53 achieves a good seal against the penetration of hot gas Ainto the space 49 and/or the escape of coolant K into the flow passage(cf. FIG. 4). The partial sealing elements 67A, 67B are in the form of,for example, of metallic sealing plates. The material selected is ableto withstand high temperatures and has sufficient elastic deformationproperties. Examples of suitable materials are a nickel-base alloy or acobalt-base alloy. This ensures that the material of the partial sealingelements 67A, 67B is selected to match the material of the rotor 25. Asa result, contamination or diffusion damage is avoided and uniform,substantially stress-free thermal expansion of the rotor 25 is possible.

FIG. 7 shows an axial plan view of part of a rotor 25 with a sealingelement 53. The rotor 25 includes a rotor disk 29. The rotor disk 29includes a first rotor-disk groove 37A and a second rotor-disk groove37B, which is arranged at a distance from the first rotor-disk groove37A in the circumferential direction of the rotor disk 29. A first rotorblade 13A and a second rotor blade 13B are inserted into the rotor disk29, the blade root 43A of the first rotor blade 13A being inserted intothe rotor-disk groove 37A, and the blade root 43B of the second rotorblade 13B engaging in the second rotor-disk groove 37B. The bladeplatform 17A of the first rotor blade 13A adjoins the blade platform 17Bof the second rotor blade 13B, and a space 49 is formed between theblade platforms 17A, 17B and the circumferential face 31.

A sealing element 53 is provided in the space 49 on the circumferentialface 31. The sealing element 53 includes a disk-sealing edge 69 and afirst partial platform-sealing edge 71A and a second partialplatform-sealing edge 71B lying opposite the disk-sealing edge 69. Thesealing element 53 is inserted into a recess 35, in particular into agroove in the circumferential face 31. The disk-sealing edge 69 adjoinsthe circumferential face 31. The first partial platform-sealing edge 71Aadjoins the disk-side base 63 of the first blade platform 17A, and thesecond partial platform-sealing edge 71B adjoins the disk-side base 63of the second blade platform 17B.

The sealing element 53 may be produced by two paired partial sealingelements 67A, 67B which engage in one another and can move in the radialand circumferential directions, as explained in FIGS. 5A to 5D and inFIGS. 6A to 6D. This allows particularly efficient sealing of the space49. In particular, axially directed leaking flows out of the space 49 orinto the space 49 are effectively prevented.

When the rotor 25 is rotating, the sealing element 53 moves radiallyoutward, away from the axis of rotation 15 of the rotor 25, parallel tothe longitudinal axis 47 under the action of centrifugal force. Thiseffect is used to achieve a significantly improved sealing action at themutually adjoining blade platforms 17A, 17B of the adjacent rotor blades13A, 13B. The sealing element 53 or each of the paired partial sealingelements 67A, 67B (not shown in FIG. 7, but cf. FIGS. 5A-5D and 6A-6D),under the action of centrifugal force, comes into contact with the bladeplatforms 17A, 17B which are at a radial distance from thecircumferential face 31 and are adjacent to one another in thecircumferential direction, and is pressed firmly onto the disk-side base63 of these platforms.

Suitable dimensioning of the recess 35, in particular of the groove, andof the sealing element 53 ensures sufficient radial mobility. Inaddition, it is provided for the sealing element 53 to be able to movein the circumferential direction of the rotor disk 29. The sealingelement 53, in particular each of the partial sealing elements 67A, 67B(which are not shown in FIG. 7, but cf. FIGS. 5A-5D and FIGS. 6A-6D),will then adjust itself under the action of all the external forces,such as for example the centrifugal force and also the normal and/orbearing forces, in order to provide its sealing action. The inclinationof the partial platform-sealing edges 71A, 71B with respect to thelongitudinal axis 47 corresponds to the inclination of the disk-sidebase 63 of the blade platforms 17A, 17B. The result is a good form fitand, on account of the inclination with respect to the longitudinal axis47, a distribution of forces over the sealing element 53 and theadjoining disk-side base 63, which is advantageous for the sealingaction. Installation conditions may lead to a gap 73 forming between theadjacent platforms 17A, 17B. This gap 73 is in flow communication withthe space 49 and can if appropriate be sealed by means of a simple gapseal element (cf. FIG. 11 and the description associated with thisfigure).

An axial plan view of part of a rotor 25 with an alternativeconfiguration of the sealing element 53 to that shown in FIG. 7 isillustrated in FIG. 8. The blade platform 17A of the first rotor blade13A is offset in the radial direction with respect to the adjoiningblade platform 17B of the second rotor blade 13B. An offset δ of thistype between blade platforms 17A, 17B which adjoin one another in thecircumferential direction generally occurs, for installation reasons,when the rotor-disk grooves 37A, 37B are inclined with respect to theaxis of rotation 15 of the rotor 25. The sealing element 53, or each ofthe partial sealing elements 67A, 67B arranged in pairs to form thesealing element 53 (this arrangement is not shown in FIG. 7, but see,for example, FIGS. 5A-5D and FIGS. 6A-6D), is equipped with anoffset-sealing edge 75, which seals the offset δ in a positively lockingmanner. The sealing concept described can therefore be flexibly appliedto various rotor geometries and installation dimensions by suitablydesigning the sealing element 53.

FIG. 9 shows a side view of a rotor blade 13 which is inserted in arotor disk 29, the sealing system 51 being arranged in the space 49 onthe circumferential-face central region 41 of the circumferential face31. The sealing system 51 is in this case designed as a labyrinthsealing system 51A, in particular a labyrinth gap sealing system 51A.The labyrinth gap sealing system 51A is produced by a plurality ofsealing elements 53, which extend in the circumferential direction ofthe rotor disk 29 and are spaced apart from one another in the axialdirection, on the circumferential-face central region 41. The individualsealing elements 53 are in this case each formed by a metal restrictorplate 77A-77E jammed into the circumferential face 41. The action of thelabyrinth gap sealing system 51A produced by the various metalrestrictor plates 77A-77E is based on restricting a flowing hot gas Aand/or a coolant K as efficiently as possible in the sealing system 51Aand, as a result, substantially reducing an axially directed leakingflow through the space 49.

The outer radial end 79 of a metal restrictor plate 77A is spaced apartfrom the disk-side base 63 of the blade platform 17 by a sealing gap 81.A residual leaking flow in the space 49 may arise through the seal gap81, as is generally the case with labyrinth gap seals 51A. By suitablydesigning and arranging the metal restrictor plates 77A-77E of thelabyrinth gap sealing system 51A, the residual leaking flow is limitedto a predetermined level. Compared to other possible labyrinth sealingsystems, the labyrinth gap sealing system 51A has the advantage that thesealing gaps 81 produce a tolerance with respect to thermally and/ormechanically induced relative expansions in the rotor 25.

An alternative configuration to the sealing system 51 shown in FIG. 9 isillustrated in FIG. 10. The sealing system 51 is likewise designed as alabyrinth gap sealing system 51A, in this case being producedintegrally, in particular by removing material from the rotor disk 29.The labyrinth gap sealing system 51A is arranged on thecircumferential-face central region 41 of the rotor disk 29. Thelabyrinth gap sealing system 51A has a plurality of sealing elements 53which extend in the circumferential direction of the rotor disk 29 andare at an axial distance from one another. The sealing elements 53 areproduced by four metal restrictor plates 77A-77D which are turned out ofthe solid rotor disk 29. This production method means that there is noneed for an additional connection element between the labyrinth gapsealing system 51A and the circumferential face 31. This is also aninexpensive solution in turns of process engineering. Furthermore,thermally induced stresses between the rotor disk 29 and the labyrinthgap sealing system 51A do not play a role, since only one material isused.

Other configurations of the sealing element 53, for example using ametal restrictor plate 77A welded onto the rotor disk, are alsopossible. At its outer radial end 79, the sealing element 53 has asealing tip 83, in particular a knife edge. The sealing gap 81 can bereduced to the smallest possible size by sharpening the outer radial end79 of the sealing element 53. In this way, residual leaking flowsthrough the space 49 are reduced further. It is also possible to bridgethe sealing gap, by producing the sealing point 83 or the knife edgewith a slight oversize compared to the radial installation dimension ofthe blade platform 17. By fitting the sealing tip 83 or the knife edgeonto the disk-side base 63 of the blade platform 17, the sealing gap 81is then bridged when the rotor blade is inserted into the rotor disk 29.In this way, the sealing gap 81 is virtually completely closed, aconsiderably improved sealing action is achieved and a possible axialleaking flow, for example caused by the flowing hot gas A or by acoolant K, in the space 49 is further reduced.

FIG. 11 shows a perspective view of part of a rotor disk 29 withinserted rotor blades 13A, with the blade root 43A of the rotor blade13A inserted in a first rotor-disk groove 37A. The blade root 43B of asecond rotor blade 13B, which is illustrated in dashed lines, isinserted in a second rotor-disk groove 37B and is arranged adjacent tothe rotor blade 13A in the circumferential direction of the rotor disk29. The sealing system 51, which is designed as a labyrinth gap sealingsystem 51A, is arranged on the circumferential face 31, on thecircumferential-face central region 41. The sealing system 51A isproduced by a plurality of sealing elements 53 which are spaced apartfrom one another along the axis of rotation 15 and extend in thecircumferential direction of the rotor disk 29. Between the bladeplatform 17A of the rotor blade 13A and the blade platform 17B of thesecond rotor blade 13B there is a substantially axially extending gap 73which is in flow communication with the space 49.

A gap sealing element 85 is provided for the purpose of sealing the gap73. The gap sealing element 85 is produced in a simple way by means of asuitable metal gap sealing plate which has a gap-sealing edge 87. Thegap-sealing edge engages in the gap 73 under the action of centrifugalforce and seals the gap 73. The gap sealing element 85 is arranged inthe space 49 in such a way that it radially adjoins the sealing system51, in particular the labyrinth gap sealing system 51A. The gap sealingelement 85 substantially prevents a leaking flow through the gap 73. Aleaking flow through the gap 73 of this type is substantially radiallydirected and may be oriented both radially outward from the space 49through the gap 73 and radially inward through the gap 73 into the space49.

A cavity 97 is formed by the platforms 17A, 17B, which adjoin oneanother in the circumferential direction of the rotor disk 29, of therotor blades 13A, 13B. This cavity adjoins the gap 73 on the radiallyouter side (box design of the rotor blades 13A, 13B). In this case, thegap sealing element 85 on the one hand prevents the possible penetrationof hot gas A from the space 49 through the gap 73 radially outward intothe cavity 97. Secondly, the cavity 97, which is sealed by the gapsealing element 85, can be acted on by a coolant K, e.g. by cooling airK. The coolant K is fed to the cavity 97 under pressure, where it isavailable for efficient internal cooling of the rotor blades 13A, 13Bwhich are subject to high thermal loads or for other cooling purposes.Furthermore, the barrier action of a pressurized coolant K in the cavity97 can be used against the hot gas A in the flow passage.

In order to be able to withstand the high temperatures which occur whenthe rotor 25 is operating and to be as resistant as possible to theoxidizing and corrosive properties of the hot gas A, the gap sealingelement 85 is made from a material which is able to withstand hightemperatures, in particular from a nickel-base or cobalt-based alloy.

FIG. 12 shows part of a view of the arrangement shown in FIG. 11 onsection line XII—XII. The gap sealing element 85 is arranged in thespace 49 and adjoins the sealing element 53 in the radially outwarddirection. When the rotor 25 is operating, the gap sealing element 85,on account of the rotation, is pressed firmly onto the disk-side base 63of the mutually adjoining platforms 17A, 17B by the centrifugal forcewhich is directed radially outward along the longitudinal axis 47, thegap sealing edge 87 engaging in the gap 73 and, as a result,substantially closing off the gap 73. The combination of the gap sealingelement 85 with the sealing system 51 on the circumferential face 41, inparticular with the labyrinth sealing system 51A (cf. FIG. 11), producesa particularly effective sealing of the space 49 with respect topossible leaking flows of hot gas A and/or of coolant K. In thiscombination, the sealing system 51 substantially reduces the axiallydirected leaking flows, while the gap sealing element 85 substantiallyreduces the radially directed leaking flows (cf. FIG. 11). In this way,the gap sealing element 85 and the sealing system 51 complement oneanother very effectively.

In addition to a rotor blade 13 being secured in a substantially axiallydirected rotor-disk groove 37 in a rotor disk 29, other ways of securingthe rotor blade are also known. The use of the sealing system describedfor alternative means of securing the rotor blade is illustrated belowin FIGS. 13 to 15.

FIG. 13 shows a perspective view of a rotor shaft 89 of a rotor 25 whichextends along an axis of rotation 15. A receiving structure 33 isproduced by a plurality of circumferential grooves 91 which are at anaxial distance from one another, extend over the entire circumference ofthe rotor shaft 89 and are machined into the circumferential face 31. Inthis case, the circumferential face 31 includes a first circumferentialface 93 and a second circumferential face 95, which lies opposite thefirst circumferential face 93 along the axis of rotation 15. The firstcircumferential face 93 and the second circumferential face 95 eachaxially adjoin a circumferential groove 91. The circumferential faces93, 95 each form an outer radial boundary surface of the rotor shaft 89.

FIG. 14 shows a sectional view of part of a rotor 25 withcircumferential groove 91 and with inserted rotor blade 13. Thecircumferential groove 91 is produced as a hammerhead groove whichreceives the blade root 43. This method of securing the blade ispreferably used for short rotor blades 13 which are subject to lowcentrifugal forces and bending moments. A sealing element 53 is providedin the space 49 on both the first circumferential face 93 and the secondcircumferential face 95. The sealing element 53 extends in thecircumferential direction of the rotor shaft 89 and engages in a recess35, in particular in a groove, in the rotor shaft 89. The sealingelement 53 is arranged radially moveably in the recess 35. When therotor shaft 89 rotates about the axis of rotation 15, the sealingelement 53 will move radially outward along the longitudinal axis 47 ofthe rotor blade 13, under the action of centrifugal force, and will bepressed firmly onto the disk-side base 63 of the blade platform 17. As aresult, the space 49 is sealed. The sealing element 53 may be assembledfrom two paired partial sealing elements 67A, 67B which engage in oneanother and are not shown in FIG. 14 (see, for example, FIG. 4 and FIGS.5A-5D and 6A-6D).

FIG. 15 shows a sectional view of part of a rotor 25 with an alternativeconfiguration of the securing of the rotor blade to that shown in FIG.14. In this case, the circumferential groove 91 is produced by aso-called circumferential fir-tree groove. Accordingly, the blade root43 of the rotor blade 13 is produced as a fir-tree root which engages inthe circumferential groove 91, in particular in the circumferentialfir-tree groove. This method of securing the rotor blade 13 producesvery effective transmission of forces to the rotor shaft 89 andparticularly reliable holding when the rotor 25 rotates about the axisof rotation 15. In a similar manner to that shown in FIG. 14, a sealingelement 53 for sealing the space 49 is provided both on the firstcircumferential face 93 and on the second circumferential face 95 in thespace 49.

The concept described for sealing the space 49 can in any event betransferred very flexibly to a rotor 25 whose rotor blade 13 is securedin a circumferential groove 91.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A turbomachine including a rotor which extendsalong an axis of rotation, the rotor comprising: a circumferential face,defined by the outer radial boundary surface of the rotor, a receivingstructure; a first rotor blade and a second rotor blade, each includinga blade root and a blade platform adjoining the blade root, the bladeroot of the first rotor blade and the blade root of the second rotorblade being inserted into the receiving structure, so that the bladeplatform of the first rotor blade and the blade platform of the secondrotor blade adjoin one another, wherein a space is formed between theblade platforms and the circumferential face; and a sealing system,provided on the circumferential face in the space, the sealing systemincluding a sealing element extending in the circumferential directionand including a first partial sealing element and a second partialsealing element, the first partial sealing element and the secondpartial sealing element engaging one another, wherein the partialsealing elements are movable in the circumferential direction relativeto one another.
 2. The turbomachine as claimed in claim 1, wherein therotor includes a rotor disk, the disk including the circumferential faceand the receiving structure, the circumferential face including a firstcircumferential-face edge and a second circumferential-face edge,opposite the first circumferential-face edge along the axis of rotation,the receiving structure including a first rotor-disk groove and a secondrotor-disk groove, which is a distance from the first rotor-disk groovein the circumferential direction of the rotor disk, and wherein theblade root of the first rotor blade is inserted into the firstrotor-disk groove and the blade root of the second rotor blade isinserted into the second rotor-disk groove.
 3. The turbomachine asclaimed in claim 2, wherein the sealing system is arranged on at leastone of the first circumferential-face edge and on the secondcircumferential-face edge.
 4. The turbomachine as claimed in claim 3,wherein a circumferential-face central region, bordered in the axialdirection by the first circumferential-face edge and the secondcircumferential-face edge, is formed on the circumferential face, andwherein the sealing system is arranged at least partially on thecircumferential-face central region.
 5. The turbomachine as claimed inclaim 2, wherein a circumferential-face central region, bordered in theaxial direction by the first circumferential-face edge and the secondcircumferential-face edge, is formed on the circumferential face, andwherein the sealing system is arranged at least partially on thecircumferential-face central region.
 6. The turbomachine as claimed inclaim 1, wherein the rotor includes at least one further sealingelement, which extends in the circumferential direction and which isarranged at an axial distance from the sealing element.
 7. Theturbomachine as claimed in claim 6, wherein at least one of the sealingelement and the further sealing element engages in a recess, in thecircumferential face.
 8. The turbomachine as claimed in claim 7, whereinthe recess is a groove.
 9. The turbomachine as claimed in claim 7,wherein at least one of the sealing element and the further sealingelement is movable in the radial direction.
 10. A turbomachine asclaimed in claim 7, wherein the sealing element includes a first partialsealing element and a second partial sealing element, the first partialsealing element and the second partial sealing element engaging in oneanother.
 11. The turbomachine as claimed in claim 6, wherein at leastone of the sealing element and the further sealing element is movable inthe radial direction.
 12. A turbomachine as claimed in claim 11, whereinthe sealing element includes a first partial sealing element and asecond partial sealing element, the first partial sealing element andthe second partial sealing element engaging in one another.
 13. Theturbomachine as claimed in claim 6, wherein the sealing element includesa first partial sealing element and a second partial sealing element,the first partial sealing element and the second partial sealing elementengaging in one another.
 14. The turbomachine as claimed in claim 13,wherein the first partial sealing element and the second partial sealingelement are movable in the circumferential direction relative to oneanother.
 15. The turbomachine as claimed in claim 14, wherein the firstpartial sealing element and the second partial sealing element eachinclude a disk-sealing edge, which adjoins the circumferential face, anda platform-sealing edge, which adjoins the blade platform.
 16. Theturbomachine as claimed in claim 13, wherein the first partial sealingelement and the second partial sealing element each include adisk-sealing edge, which adjoins the circumferential face, and aplatform-sealing edge, which adjoins the blade platform.
 17. Theturbomachine as claimed in claim 13, wherein the first partial sealingelement and the second partial sealing element overlap one another, theplatform-sealing edge and the disk-sealing edge of the first partialsealing element being adjacent to the platform-sealing edge anddisk-sealing edge, respectively, of the second partial sealing element.18. The turbomachine as claimed in claim 6 wherein the sealing elementis produced from a highly heat-resistant material.
 19. The turbomachineof claim 18, wherein the sealing element is produced from at least oneof a nickel-base and cobalt-base alloy.
 20. The turbomachine as claimedin claim 1, wherein the turbomachine is a gas turbine.
 21. Theturbomachine as claimed in claim 1, wherein the receiving structureincludes a circumferential groove, wherein the circumferential faceincludes a first circumferential face and a second circumferential facewhich lies opposite the first circumferential face along the axis ofrotation, wherein the first and second circumferential faces eachaxially adjoin the circumferential groove, and wherein the sealingsystem is provided on at least one of the first and on the secondcircumferential face in the space.
 22. A rotor, comprising: acircumferential face, defined by the outer radial boundary surface ofthe rotor, a receiving structure; a first rotor blade and a second rotorblade, each including a blade root and a blade platform adjoining theblade root, the blade root of the first rotor blade and the blade rootof the second rotor blade being inserted into the receiving structure,so that the blade platform of the first rotor blade and the bladeplatform of the second rotor blade adjoin one another, wherein a spaceis formed between the blade platforms and the circumferential face; anda sealing system, provided on the circumferential face in the space, thesealing system including a sealing element extending in thecircumferential direction and including a first partial sealing elementand a second partial sealing element, the first partial sealing elementand the second partial sealing element engaging one another, wherein thepartial sealing elements are movable in the circumferential directionrelative to one another.
 23. A rotor as claimed in claim 22, wherein therotor includes a rotor disk, the disk including the circumferential faceand the receiving structure, the circumferential face including a firstcircumferential-face edge and a second circumferential-face edge,opposite the first circumferential-face edge along the axis of rotation,the receiving structure including a first rotor-disk groove and a secondrotor-disk groove, which is a distance from the first rotor-disk groovein the circumferential direction of the rotor disk, and wherein theblade root of the first rotor blade is inserted into the firstrotor-disk groove and the blade root of the second rotor blade isinserted into the second rotor-disk groove.
 24. A rotor as claimed inclaim 23, wherein the sealing system is arranged on at least one of thefirst circumferential-face edge and on the second circumferential-faceedge.
 25. A rotor as claimed in claim 22, wherein the rotor includes atleast one further sealing element, which extends in the circumferentialdirection and which is arranged at an axial distance from the sealingelement.
 26. A rotor as claimed in claim 25, wherein at least one of thesealing element and the further sealing element engages in a recess, inthe circumferential face.
 27. A rotor as claimed in claim 25, wherein atleast one of the sealing element and the further sealing element ismovable in the radial direction.